Half marathon world record holder Abraham Kiptum has been provisionally suspended by the Athletics Integrity Unit for an Athlete Biological Passport violation under the International Asssociation of Athletics Federation's anti-doping rules.

Kiptum was a relatively unknown runner when he ran 58:18 at the Valencia Half Marathon in October and broke Zersenay Tadese's previous world record of 58:23 set in 2010 in Lisbon. The world record was ratified by the IAAF on Dec. 6, 2018.

Kiptum was slated to run in Sunday's London Marathon. Eight hours before the AIU's announcement, he posted about his excitement to run in Sunday's race. He wrote, "Two days to debut in one of the best marathons!!"

He ran a half marathon last month in Bahrain, where he placed sixth in 60:04.

Kiptum followed up his half marathon world record with a 2:04:16 performance at the Abu Dhabi Marathon in December, which later was revealed to have a short course. His personal best at the marathon distance is 2:05:26 from the 2017 Amsterdam Marathon.

The London Marathon will be contested on Sunday and features a showdown between world record holder Eliud Kipchoge and four-time Olympic gold medalist Mo Farah.